This invention relates to a method and apparatus for the electric butt welding or flash butt welding of workpieces having rod-like ends. The invention is, in particular, concerned with the welding of the ends of chain links bent into C-shape on which there can be positioned electrodes and at least one positioning device which operates in the upsetting direction.
In welding machines known heretofore, particularly in welding machines for welding the ends of chain links bent into a C-shape, subsequent to the introduction of the chain link to be welded, the upsetting tools for holding and centering of the chain link have been advanced and thereupon, after a short delay, the electrodes were positioned on the two ends to be welded. Thereafter, at a moment fixedly preset in a control means, the welding current was turned on to carry out the welding program with the subsequent upsetting of the workpiece. This otherwise reliable process, however, fails to take into consideration the tolerances in the shape of the workpieces to be welded, particularly chain links bent into C-shape. It is precisely these tolerances, however, which, to a certain extent, may have an effect on the quality of the weld, particularly because upon starting the welding current, the pressure with which the faces to be welded are forced in engagement with one another, may significantly differ dependent upon the different shape deviations within the tolerance range.